Coronavirus infections from 2002 to 2021: neuropsychiatric manifestations

Coronaviruses have been known to infect humans for several decades and there are four endemic subtypes: HCoV (human coronavirus) −229E, -NL63, -OC43 and -HKU1. These mainly cause a mild upper respiratory illness, but occasionally in vulnerable individuals they can result in more severe respiratory disease and, rarely, CNS involvement. Prior exposure to these viruses has also been associated with an increased odds of having a major psychiatric illness. The severe acute respiratory syndrome (SARS), caused by SARS-CoV, started in 2002 and, as well as causing a more severe respiratory phenotype, was also associated with delirium and affective symptoms acutely. Psychosis occurred in about 1% of individuals and was generally thought to be due to corticosteroid administration. The Middle East respiratory syndrome (MERS), caused by MERS-CoV, revealed similar findings. Survivors of both SARS and MERS reported persistent physical and psychological symptoms at least several months after the acute illness. The reported neuropsychiatric symptoms of COVID-19 range from the common symptoms of systemic and upper respiratory infections to severe and disabling conditions. Delirium has been described using varying terminology; as well as being a possible presenting feature of COVID-19, it has also been shown to be a marker of severe disease. Stroke, both ischaemic and haemorrhagic, have been reported to be more common in COVID-19 than in other medical illnesses. Mood and anxiety disorders are likely to be common at follow-up, while psychosis remains rare and controversial. ‘Long Covid’ is likely to represent a highly clinically and aetiologically heterogeneous group.